Paper processing operations often utilize machinery having elongated rotating rolls, which may be several meters in length, for transporting a web of material, cutting the web into individual sheets, and folding or interfolding the individual sheets into a desired folded pattern. Such rolls typically rotate at high speed and are generally of a robust construction having considerable weight. Adjacent rolls often interact with one another in a manner which subjects the roll to considerable side loading and/or bending loading. Such rolls also typically include fluid passages therein, for applying vacuum and/or compressed air to rows of fluid ports disposed in one or more arrays along an angular portion of the periphery of the roll. Even where only vacuum, or low pressure air is applied to the fluid ports over the angular portion of the roll, the length of such rolls results in considerable additional bending loads being applied along the axis of the roll as a result of the vacuum and/or fluid pressure.
In the past, elongated rolls of the type used in the paper processing industry have typically relied more-or-less completely upon bearings disposed at opposite axial ends of the roll to provide rotational support of the roll. Such support arrangements utilizing bearings located at opposite axial ends of a roll are disclosed in: U.S. Pat. No. 5,230,456 to German; U.S. Pat. No. 7,367,264 to Beaudry; U.S. Pat. No. 6,585,139 to Holtmann; U.S. Pat. No. 4,190,241 to Kreuger; U.S. Pat. No. 6,488,194 to Couturier; U.S. Pat. No. 6,296,601 to Couturier; and U.S. Pat. No. 4,254,947 to Trogan.
Where operation of a roll supported solely at opposite axial ends required the provision of vacuum or air pressure at fluid ports located along the outer periphery of the roll, two prior approaches have been utilized. In one approach, as exemplified by U.S. Pat. No. 5,230,456 to German and U.S. Pat. No. 6,585,139 to Holtmann, vacuum and/or air pressure is provided through a stationary inner tube about which the roll rotates on bearings disposed at opposite axial ends of the roll. Typically, non-load bearing, radially extending walls affixed to the inner tube define a suction box area, or a pressure box area over an angular portion of the space between the stationary inner tube and the roll. This type of arrangement does not lend itself well to use in rolls rotating at high speed and having considerable lengths. In addition, where the operation performed by the roll includes gripping or folding a sheet passing over the roll, or for rolls having cutting blades mounted therein, a suction or pressure box structure cannot typically be used, because cutting blades, grippers and tucker elements of the folding rolls must typically be housed within the periphery of the roll. Even where such elements are not required to extend into the roll, the prior structures utilizing suction or pressure boxes are simply not structurally stiff and strong enough for operation at the high rotational speeds and with the substantial side loads required for economical operation in modern paper processing operations.
Prior roll structures utilizing suction or pressure boxes are also typically not capable of providing the sophisticated degree of control of vacuum necessary for modern paper processing operations. In such operations, for example, it may be necessary to apply vacuum at several positions around the periphery of the roll.
A more modern approach to providing vacuum and/or pressure to ports or operating elements disposed along the length of elongated rolls used in modern paper processing is illustrated by: U.S. Pat. No. 4,254,947 to Trogan; U.S. Pat. No. 6,296,601 to Couturier; and U.S. Pat. No. 6,488,194 to Couturier. In these more modern approaches, a roll is supported for rotation at high speed by bearings disposed at opposite axial ends of the roll. The roll includes one or more fluid passages extending longitudinally into the roll from one or both ends of the rolls. These longitudinally extending fluid passages are connected within the roll to radially extending passages opening through the outer periphery of the roll, or connecting with air-actuated elements mounted within the periphery of the roll at various locations along the longitudinal length of the roll.
A vacuum timing device, having one or more circumferentially shaped grooves abuts one or both axial ends of the roll, for directing fluid or applying vacuum to the axial ends of the longitudinally extending bores within the roll over a desired angular portion of the rotation of the roll. While this arrangement generally has worked well, this approach imposes certain structural and physical limitations on the operational speed of the processing machinery and methods.
As the length of rolls utilized for processing paper has increased, it has become increasingly difficult to build enough strength and stiffness into the complex profiles used in modern paper processing rolls for high speed operation with the rolls supported only at opposite axial ends thereof. Also, because dynamic loads inherent in the operation of rotating machinery increase at an exponential rate with an increase in speed, it has become increasingly difficult to build rolls having the highly convoluted shapes required to accommodate internal gripping, cutting and tucking structures, without compromising operation or structural strength of the roll arrangement.
Another undesirable limitation of the present approach of having vacuum and/or pressure applied through a timing device disposed at one or both axial ends of a rotating roll derives from the fact that it takes too long for vacuum to become uniform, or pressure to build along the extended longitudinal length of the roll speeds and widths increase. Stated another way, the prior arrangements have too much time lag and resistance to fluid flow for operation at increased speeds and over ever longer roll widths as is desirable to continue advancement and enhancement of the output rate and quality of products being produced with the roll.
It is desirable, therefore, to address one or more of the problems and limitations described above with present processing rolls in an improved roll apparatus and method. Specifically, it is desirable to provide a new rotating roll and apparatus capable of operating at higher speeds and with greater roll lengths. Where the operation of the roll requires provision of vacuum, air, or other fluids at ports extending from the surface of the roll at selected angular locations along the longitudinal length of the roll, it is desirable to provide an improved apparatus and method for enhancing fluid flow in a manner more amenable to accurate control, with less time lag and more uniform application along an entire array of such fluid ports.